The invention relates to polymeric halogenated organophosphorus diols. More particularly, the invention relates to processes for preparing these novel polymeric materials and utilizing the same along with other polyols, as co-reactants in the production of polyurethanes. Polyurethanes containing these novel polymeric materials have superior flame retardant properties when compared to conventional polyurethanes.
Organophosphorus compounds containing halogens are well known in the art. Many compositions of this broad class of materials have been claimed as flame retardants for a variety of polymers, including polyurethanes. A substantial portion of such materials are of the additive type. That is, these materials are not chemically bound to the polymer backbone. Such additive flame retardants are described, for example, in the U.S. Pat. No. 3,192,242. The organophosphorus materials disclosed in this patent have the general formula: ##EQU1## wherein X is a halogen such as bromine or chlorine and Y is a haloalkoxy group.
Reactive type flame retardants usually possess at least two reactive sites through which they are chemically bound to the polymer backbone. These retardants are superior to the additive type retardants, because not only will they not evaporate, sublime or leach out of the polymer substrate during use or processing but they also form an integral part of the polymer structure.
Reactive type flame retardants such as chlorine containing phosphate polyols have been employed to improve polyurethane resins. These reactive flame retardants are typified in U.S. Pat. No. 3,423,486.
While various known reactive type flame retardants are useful in rigid type polyurethane foam, they may not be employed advantageously in the production of flexible type foam. For example, the above mentioned phosphate polyols are tetrafunctional monomers, that is they possess large OH Numbers, and this characteristic makes them unsuitable as correactants in a flexible foam formulation which requires polyols having a functionality in the range from 2 to 2.5, as well as an OH number of 100 of preferably less.
The polymeric halogenated organophosphorus diols of the invention are prepared by chlorinating or brominating a spirocyclic phosphite at temperatures from about -50.degree.C. to +50.degree.C, and condensing halogenated reaction product with a diol in the presence of an acid acceptor. These novel diols possess hydroxyl groups capable of forming urethane linkages with isocyanates. Although the diols of the invention may be used alone with polyisocyanates to form polyurethane-type polymers they may also be employed in admixture with other suitable polyols.
The novel compositions of this invention are especially useful in the production of flexible urethane foams. It was found that these polymeric diols can be incorporated into the foam in amounts sufficient to render the foam flame-resistant without significantly affecting physical properties of the polymer substrate.